2/ 🧵 If you find yourself in cold surroundings, sensors in your skin recognize this and signal the brain.

These lead your body to react in two ways: generating heat and conserving as much body heat as feasible.

Some of these reactions occur unintentionally; others are deliberate. First, blood vessels just under the skin constrict, lowering the heat output to the surroundings.

Your skin feels cold, but more heat stays in your core to guard essential organs. There is less blood also reaching the extremities of the body. You thus develop a chilly nose, hands, and feet. Furthermore, you start generating heat by alternately tightening and releasing your muscles.